Almost all the graph objects have upper case and lower case first letter versions. I have read the api docs. It still can’t come up with a simple rational for the difference. If you could help me understand better I would be grateful.
From what I understand, the Scatter class is used to create the graph object and return the lines or markers plots or both depending on your choice.
While the plotly.graph_objects.scatter classes are utilise when you want to plot the error bars like the ones utilized in the examples in the link: px.scatter, check the error bar plot.
I believe the scatter plot is a package, a class which contains other functions (11 of them ) of the scatter plot like the ERRORX and ERRORY classes and the Scatter class might be inheriting the class scatter and thereby having those functions.
Check plotly.graph_objects.scatter package